All fluids tend to flow from areas of high pressure to areas of lower pressure. But because of the rotation of the Earth, Coriolis effect causes the wind to circulate around areas of high and low pressure. The direction of this circulation is depends on the location (northern or southern hemisphere), and whether the area is one of high or low pressure. The outcome of these effects is predicted by Buys Ballot’s Law, which states that when standing with one’s back to the wind, the low pressure area is on your left.
If an aeroplane is subjected to a crosswind it will drift in the direction of that wind. In this question the aeroplane is drifting to the right, so the wind must be coming from its left side. Applying Buys Ballot’s law this means that the aeroplane in this question must be flying towards the area of low pressure.
If you need a more detailed explanation you should read up on coriolis effect, which is part of the ATPL Met syllabus.